A VETERAN nurse has likened conditions in the asylum seeker detention centre on Nauru to a concentration camp.

Marianne Evers worked at the centre for three weeks late last year and says the conditions were completely appalling.

"I actually liken it to a concentration camp," Ms Evers, who has more than 40 years nursing experience, told ABC Television tonight.

"But the Australians don't have the guts to kill these people and put them out of their misery. Because miserable it is."

The Dutch-born Australian citizen, who broke a confidentiality agreement by coming forward, said she saw numerous attempted suicides and other instances of self-harm during her brief stay on the tiny Pacific island.

She says she also heard allegations of sexual assault from other staff members but did not herself witness anything.

Department of Immigration and Citizenship spokesman Sandi Logan questioned why it took so long for Ms Evers to come forward.

"I think invoking concentration camps is a disgrace to be quite honest," he said.

"I don't think anyone should be throwing terms like concentration camp around with such abandon."